View to the south
with 209 Mile Canyon entering from the lower right edge and
joining the Colorado River just before the large flat island
in Granite Park. The diagonal line starting about midway on
the left edge (and trending toward the river in the distance)
is the main branch of the Hurricane Fault. Movement along the
fault fractures underlying rock making it easier for periodic
rainstorms to erode away the surface. Thus, valleys and
canyons tend to develop along fault lines.
One of the side branches of the fault just grazes
the river near the island in Granite Park, and then continues
south-southeastward from there. Uplift to the east of this
branch has brought Precambrian schist and granite to the
surface to the left of the river just upstream from the
Downstream from here the rock walls next to the
river here are composed of the Tapeats to Supai Paleozoic
layers. However, the strata generally slope upward to the
south, and as a result the Precambrian basement rocks will
begin to show up again – especially to the left (east) where
they have been uplifted to the east of the Hurricane Fault.
There are still patches of the lava flows near the river, but
they are becoming steadily sparser as the river gets further
from the volcanic source zones.
In the western part of the Grand Canyon, the
Hualapai Drainage system was eroding broad valleys down to the
Esplanade Sandstone surface long before the Colorado found its
new route across the Kaibab Plateau. As a result the outer rim
formed by the Kaibab, Toroweap, Coconino, and Hermit
formations has eroded back to where it usually cannot be seen
from the river.
View to the
south with Three Springs Canyon entering from the left
(east) slightly above the midpoint of the picture. Lower
Granite Gorge begins just after Three Springs Canyon as
the 1.7 billion year old Precambrian metamorphic rocks
begin to rise above river level.
If you are rafting the river, there is an
orange-colored spring on the left side of the river just
before it starts its gradual turn to the left (Just above
the bottom edge of the picture). This is “Pumpkin Spring”
which is also known as “Charlie Brown’s Great Pumpkin”.
Drinking the water from the spring is not advised as it
has a high arsenic content.
The Hurricane Fault stays just to the left of
the river through this section. The maximum displacement
along the fault is some 2,400 feet about where it
intersects Three Springs Canyon. The 2,400 foot
displacement is actually partitioned across a series of
local faults spread across the entire fault zone.
miles 200 to 208
river miles 216 to 224
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